Single-strand DNA translation initiation step analyzed by Isothermal Titration Calorimetry

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• The direct translation of single-strand DNA (ssDNA) into proteins remains a long-standing question in molecular biology since the 1960s.
• Previous studies have shown conflicting results regarding the functional translation of ssDNA, but consistently indicated similar initiation behaviors compared to RNA.

Purpose of the Study:

• To investigate the thermodynamic properties of the interaction between ssDNA and the translational machinery.
• To determine if ssDNA can bind to the S30 extract of Escherichia coli and initiate translation.

Main Methods:

• Isothermal Titration Calorimetry (ITC) was employed to measure the thermodynamic constants of interaction.
• Antibiotic interference assays were used to confirm the specificity of the initiation complex formation.

Main Results:

• The dissociation constants for the binding of ssDNA and its corresponding RNA sequence to the S30 extract were found to be in a similar range (K(d) ≈ 10^-8 M).
• The binding affinity was independent of the specific ssDNA template used.
• Antibiotic interference confirmed that ssDNA can form an initiation complex, similar to RNA.

Conclusions:

• Single-strand DNA can engage in the initiation step of translation with bacterial ribosomal machinery.
• The data suggest that while initiation is feasible, the elongation phase is the bottleneck for functional ssDNA translation.